Field of the Disclosure
The present disclosure relates to a power net system of a fuel cell vehicle and a method for controlling the same, and more particularly, to a power net system of a fuel cell vehicle, capable of removing a voltage remaining in a main bus of the power net as well as a voltage of a fuel cell stack during a dangerous situation such as collision, and preventing a risk of exposure to a high voltage, and a method for controlling the same.
Description of the Related Art
A fuel cell system which is applied to a hydrogen fuel cell vehicle as one of environment-friendly vehicles includes a fuel cell stack configured to generate electrical energy from an electrochemical reaction of reaction gas; a hydrogen supply device configured to supply hydrogen as fuel to the fuel cell stack; an air supply device configured to supply air containing oxygen to the fuel cell stack, the oxygen serving as an oxidizer required for an electrochemical reaction; and a heat and water management system configured to adjust the operation temperature of the fuel cell stack to an optimal temperature by discharging heat as a by-product of the electrochemical reaction of the fuel cell stack to the exterior, and perform a water management function.
A fuel cell load device for decreasing and removing the voltage of the fuel cell stack is connected to the fuel cell stack to remove oxygen inside the fuel cell stack while and after the start of the fuel cell vehicle is stopped. The oxygen introduced to the fuel cell stack is removed with remaining hydrogen of the anode, while the current is consumed by the fuel cell load device. When the anode is out of hydrogen (e.g., no hydrogen remains), oxygen cannot be consumed. Thus, to prevent such a situation, the wakeup technology is used to periodically supply hydrogen to the anode. In other words, the fuel cell vehicle requires a separate post process for decreasing the voltage of the fuel cell stack by removing remaining air inside the fuel cell stack after start off, unlike the internal-combustion engine.
To prevent the deterioration of the fuel cell stack and a risk of exposure to a high voltage. When a voltage is formed when oxygen exists in the anode, carbon corrosion occurs at the cathode. Thus, the fuel cell vehicle requires a process of removing oxygen inside the fuel cell stack, preventing an additional oxygen flow, and removing oxygen which is introduced. When a dangerous situation such as collision occurs, the conventional fuel cell vehicle is forced to use the fuel cell load device to decrease the voltage of the fuel cell stack, thereby preventing a risk of exposure to a high voltage.
However, the conventional fuel cell vehicle simply decreases the voltage of the fuel cell stack, and a high voltage remains at a main bus of a power net connected to the fuel cell stack and another high-voltage load. Thus, a risk for exposure to a high voltage still exists. In particular, when the conventional fuel cell vehicle is applied to a fuel cell hybrid vehicle having a main bus connected to a high-voltage battery, a risk of exposure to a high voltage remaining in the main bus may increase.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.